Solar Panel Guide Discussion

Martyn1981

Hemel_Saint wrote: »

Cheers Martyn
Great summary.

Can I just ask you guys if you can clarify what I should be asking the next installers to quote for, if I go SW only...

• As many panels as poss on SW roof (250w or 285w)
• a single 3.68kW inverter
• An Immersion Throttle/Converter (ie Apollo GEM/I Boost)
• OWL monitor
• no to a Voltage Optimiser

all for under £5k.
Is that realistic?

sorry to hog the board, but this advice is fantastic and hopefully a help to others too (that’s my excuse to keep asking loads of Qs on here!!!)

cheers all
Mark

Hiya Mark. You're not hogging the board. Any questions that raise debate and info will also be read by non-posters, so hopefully the advice spreads.

I think you should be able to get a 4kWp system (250Wp or 285Wp) plus diverter, and possibly a monitor for under £5k. I think you should aim for closer to £4k.

The diverter will help your numbers a bit if it saves you another £50 - £80 or so in oil costs.

I don't think you need to worry about haggling, instead be honest, point out the income, and that you really need to get the price down to sub £4.5k or it just won't work for you.


For 4KWp it would be entirely normal to install a 3.68kW capped inverter. That way no prior agreement is needed from the DNO, they just get notified after the install to update their records.

For 5kWp, if that'll fit on your roof, you will also be fine with a 3.68kW capped inverter, but there will be times when the system is sitting at 3.68kW and you know some capping (waste) is taking place, but most of the time, in the winter, poor weather, early and late etc you'll be fine, and the higher capacity will help to improve the efficiency of the inverter.


DOH! Didn't see the next page, and T beat to me ....... everything!

Mart.

Martyn1981

Hemel_Saint wrote: »

From the plans from the 1st quote.
29.6 ft wide
15ft deep
with a chimney fairly central.

they had 14x 285w around the Chimney stack.
If they use all space, 16 maybe 17.

cheers
Mark

Mark, see bold. That changes things, and suggests you might be better off going with a SolarEdge system.

Again, nothing wrong with SE kit, it's brilliant. So if needed, go for it.

Mart.

Martyn1981

Hemel_Saint wrote: »

From the plans from the 1st quote.
29.6 ft wide
15ft deep
with a chimney fairly central.

they had 14x 285w around the Chimney stack.
If they use all space, 16 maybe 17.

cheers
Mark

So that translates to 9m by 4.5m. Using a standard(ish) panel size of 1.6m by 1m you could probably fit 8 panels portrait or 5 panels landscape. Both would work out at 8m allowing for space at each end and 20mm gaps between. The 8m 'match' also allows for a combination of layouts without it looking too odd.

So the question is how much height is ueable. You need to leave some space below the ridge tiles, and space at the bottom to prevent wind lift, and rain flowing over the gutter.

So options might be 2 rows portrait = 3.2m (x8 = 16)
3 landscape 3m (x5 = 15)
4 landscape 4m (x5 = 20)
1 landscape and 2 portrait = 4.2 m (1 x 5 + 2 x 8 = 21)
2 landscape and 1 portrait = 3.6m (2 x 5 + 1 x 8 = 18)

Then the issue is where is the chimney, and which combination fits best with the least loss of panels. Hopefully 16+ panels is possible, and that'll give you a lovely system size.

[Edit: Another thought, might be 2m by 1m panels, and 2 rows of 8. That would give you 16 panels of ~300Wp each, but depends on chimney, and 2m panels are less common. M.]

Mart.

Hemel_Saint

this is the scematic from the quote for the SW roof.

[IMG]http://forums.moneysavingexpert.com/<a href=http://s223.photobucket.com/user/HemelSaint76/media/Roof panels SW.jpg.html target=_blank rel=nofollow>[/img]

Cardew

No shading from chimney stack on SW roof? How high is stack?

Hemel_Saint

Cardew wrote: »

No shading from chimney stack on SW roof? How high is stack?

21 bricks high on the stack at the front-end (highest), so is around 5.3ft.

Martyn1981

Hemel_Saint wrote: »

21 bricks high on the stack at the front-end (highest), so is around 5.3ft.

Mark, is removing the chimney an option? Presumably, not too hard a job if the scaffolding is up there. Would the house look odd compared to others, have any others removed chimney, is the chimney used in any way?

Looking at the schematic there's plenty of space. You can pack the panels right up against the chimney if you have a SolarEdge system. The only place to avoid would be directly above and behind the chimney - the panel would still work, but might be a financial waste as it would be in shade most of the day, one way or another.

I appreciate it's only a schematic, but suggests you could get a row portrait under the chimney, so that's 8 panels, then perhaps 2 rows of 2 landscape either side of the roof, so another 8 panels.

16 285Wp = 4.56kWp. Given that there will be a bit of shading, most of the time, a 3.68kW inverter probably wouldn't cap much at all.

Second thoughts, the schematic shows 2 portrait and 1 landscape, so they've estimated 4.2m of useable height, so perhaps 4 rows of landscape, 5 panels on the bottom row and 2 + 2 panels on the next 3 rows, giving you 17 panels, and quite a nice layout too.

Mart.

tunnel

Chimney where it is equals solaredge or micro inverters(they do the same thing).
It shouldn't increase the price too much either, maybe a few hundred quid on the total so still doable for under £5k for a 4kWp system, although I'm with Mart on going larger if poss with the 3.68 cap inverter.
Use your bartering skills and you may just end up with a 5kWp system for under £5k....now that would be impressive

Hemel_Saint

tunnel wrote: »

....Use your bartering skills and you may just end up with a 5kWp system for under £5k....now that would be impressive

no pressure then!

I have spoken with a company recommneded by one of the forum members. I will updtae you on what they say.
....and if they read this forum.... they now know what price we need!!

cheers
Mark

zeupater

Hi

Just a consideration to stir into the thought-train .... we have a chimney in a similar position in the roof slope (although not a roof with pv) and occasionally need access to clean out the moss, sand, soil etc which collects in the lead back gutter and side flashing. Last Autumn the chimney pot received a present in the form of a shiny new cowl so whilst up there I removed loads of rubbish - as such I'd be wary of restricting access to the chimney stack or the leadwork around it unless it was considered totally necessary ....

HTH
Z